Abstract Detail

Thousands of fossilized logs of Middle Miocene age are entombed in the Columbia River Basalts of central Washington State, USA. Professor George Beck of Central Washington University undertook a comprehensive study of these woods beginning in the 1930's. Beck’s 1945 paper in the Journal of Forestry listed the wood types he recognized at 12 localities. Vantage, the area of the Ginkgo Petrified Forest, had the most diverse wood assemblage, and, to our knowledge, is the single most diverse Miocene wood locality in the U.S. with 34 distinctive dicot wood types and six gymnosperms. In the 1960's Prakash and Barghoorn published three papers providing formal descriptions for a number of species from Beck's main collecting horizon at Vantage. We've examined the specimens from those studies as well as additional samples collected by Beck. Our intent is to provide an overview of the Vantage wood assemblage, using resources not available in the mid-1900’s (including InsideWood) to reevaluate the fossil woods’ affinities to extant plants, and describe taxa not included in the 1960s papers (e.g. Hamamelidoxylon, Prunus, Pseudotsuga, Taxus). The MAT of the Vantage wood assemblage was estimated at 12.1-12.8o C based on % incidence of selected dicot wood features using formulae from Wiemann et al. 1998, 1999. There is considerable overlap in the genera at Vantage and in similarly aged megafossil and pollen floras from the Pacific Northwest, with most related to genera now occurring in eastern Asia and eastern North America. Comparison of the Vantage wood assemblage to older and younger fossil wood assemblages shows changes through time in the incidences of wood anatomical features considered ecologically significant, both within selected clades as well as woods in general.